1. Field of the Invention
The present invention relates to a magnetoresistive element and a method of manufacturing the same, e.g., a magnetoresistive element capable of recording data by bidirectionally supplying an electric current, and a method of manufacturing the same.
2. Description of the Related Art
A magnetic random access memory (MRAM) is known as a kind of a semiconductor memory. The MRAM is a device that performs a memory operation by storing binary 1 or 0 in a memory cell by using the magnetoresistive effect. Since the MRAM is a nonvolatile, high-speed, high-integration, high-reliability device, it is regarded as a candidate for a memory device capable of replacing, e.g., an SRAM, pseudo-SRAM (PSRAM), or DRAM.
Many MRAMs using an element exhibiting the tunneling magnetoresistive (TMR) effect among the magnetoresistive effects have been reported. As the TMR effect element, a magnetic tunnel junction (MTJ) element is generally used. This MTJ element has a stacked structure including two ferromagnetic layers and a tunnel barrier layer sandwiched between them, and uses a magnetoresistance change obtained by the spin-polarized tunneling effect. The MTJ element can take a low-resistance state and high-resistance state in accordance with the magnetization arrangement of the two ferromagnetic layers. A binary digit can be recorded in the MTJ element by defining the low-resistance state as binary 0 and the high-resistance state as binary 1.
An interlayer dielectric film is normally formed around the MTJ element. Oxygen contained in this interlayer dielectric film or a gas produced when the interlayer dielectric film is formed degrades the characteristics of the magnetic layers and tunnel barrier layer forming the MTJ element. This degrades the magnetic characteristics of the MTJ element, and consequently destroys the retained binary digit.
As a related technique of this kind, a technique that suppresses oxidation or reduction of a tunnel insulating layer by covering the circumferential surface of the MTJ element with a barrier layer has been disclosed (Jpn. Pat. Appln. KOKAI Publication No. 2003-243630).